Posted
by
samzenpuson Wednesday October 15, 2008 @09:55PM
from the gentlemen-we-can-rebuild-him dept.

GalaticGrub writes "A pair of paralyzed monkeys regained the ability to move their arms after researchers wired individual neurons to the monkeys' arm muscles. A team of researchers at the University of Washington temporarily paralyzed each monkey's arm, then rerouted brain signals from a single neuron in the motor cortex around the blocked nerve pathway via a computer. When the neuron fired above a certain rate, the computer translated the signal into a jolt of electricity to the arm muscle, causing it to contract. The monkeys practiced moving their arms by playing a video game."

It's certainly true that proprioception (the ability to sense joint location) and sensation of muscle tension are useful feedback systems in coordinating limb movements. It's well known in the field (I'm a neuroscientist), however, that several neurological conditions rob patients of these sensations and they're still able to move their limbs effectively (though not perfectly). I'd guess that a patient who was paralyzed wouldn't mind being able to move their arms again, even if they couldn't feel where they were without looking.

I wouldn't be too sure. This is just the latest in a long string of research findings that point toward an astounding degree of neural plasticity in adults. At this point, if I had to guess, I'd say that wiring one sensory nerve from the general area back to a single neuron would end up restoring a noticeable degree of "feeling".

Hopefully the diaphragm is able to be connected like this, I believe it would as it behaves as a skeletal muscle?

Yes, it does. However, the question is whether you can get the respiratory center of the brain to recognize the "bypass" - else you could breathe voluntarily, but would stop as soon as you stop thinking about it (or fall asleep, for example).

The fun part about those is that, while binary signals may work for them, I would really prefer no sensation to the choice of "OK" and "OMG MY HAND IS ON FIRE" with no gradient between.

Nerves also deal in binary information only, as far as the value is concerned - the intensity of the sensation is encoded in the frequency of the pulses. For low intensity, the nerve only fires once in a while, for higher intensities the frequency can go up all the way to the inverse of the refractory period (the time the nerve needs to "reset" after a pulse).